McCaskill's head 'about to pop off' over defense contracting mess

Sen. Claire McCaskill (D-Mo.) tweeted that "the top of my head is about to pop off" during a hearing regarding defense contracting reform.

The oft-tweeting senator made her animated comment during a Senate Homeland Security Committee hearing featuring witnesses from the Department of Defense and the Government Accountability Office (GAO):

Gonna be some tuf ?s for witnesses in a few at this hearng. Unbelievable problms at Def Contrctng Agncy. Top of my head is about to pop off.